Printed circuit boards (PCBs) are used in many applications for routing signals between two or more devices. A typical PCB includes a set of stacked, horizontal metallization layers separated by a set of stacked, horizontal dielectric (electrically-insulating) layers, respectively. For manufacturing purposes, a PCB may further include a set of vertical metallized vias or simply vias (also known as plated-thru holes) electrically-connecting the top or upper metallization layer to the bottom or lower metallization layer.
Often a high-speed data signal (e.g., in the gigabits per second (Gbps) range) is routed through various metallization layers and a via from a transmitting device to a receiving device. As an example, the data signal may be routed through a top metallization layer, a metalized via, and an intermediate (e.g., third from the top) metallization layer. As a result of such construction, the portion of the via below the intermediate metallization layer, defined as a stub or non-signal-path portion of the via, is not actually needed for routing the signal, and often produces a resonance that adversely affects the data signal.
Accordingly, several PCB implementations are described herein that reduces the adverse effects on data signals as a result of such stubs.